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Entry  Mon Aug 10 22:18:19 2015, Ignacio, Update, IOO, Ready to do some online mode cleaner subtraction stsx.pngperformance.pngfilter.zip
    Reply  Tue Aug 11 11:30:19 2015, Ignacio, Update, IOO, SISO (T240-X) FF of MCL MCL.pngMCTRANS.pngYARM.png
       Reply  Wed Aug 12 01:32:18 2015, Ignacio, Update, IOO, Improved SISO (T240-X) FF of MCL filter.pngstsx.pngmclonline.pngyarmonline.pngsub.png
    Reply  Wed Aug 19 01:45:10 2015, Ignacio, Update, IOO, Doubly Improved SISO (T240-X) FF of MCL 6x
       Reply  Thu Aug 20 11:09:10 2015, rana, Update, IOO, some points about seismic FF 
       Reply  Thu Aug 27 01:41:41 2015, Ignacio, Update, IOO, Triply Improved SISO (T240-X) FF of MCL 1.png2.png4.png5.png3.png
          Reply  Fri Aug 28 00:59:55 2015, Ignacio, Update, IOO, Final SISO FF Wiener Filter for MCL bode.png2.png3.png4.png6.png
Message ID: 11496     Entry time: Wed Aug 12 01:32:18 2015     In reply to: 11492
Author: Ignacio 
Type: Update 
Category: IOO 
Subject: Improved SISO (T240-X) FF of MCL 

In my previous elog:11492, I stated that in order to improve the subtraction and reduce the injection of high frequency noise we want the filter's magnitude to have a 1/f rolloff.

I implemented this scheme on the filter SISO filter previously analyzed. The results are shown below.

The filters bode plot:

The nice 1/f rollof is the main change here. Everything else remained pretty much the same.

The predicted FIR and IIR subtractions:

Everything looks right but that hump at 8 Hz. I used 8 pairs of poles/zeros to get this subtraction.

The online MCL subtraction:

This looks better than I expected. One has to keep in mind that I ran this at 1 AM. I wonder how well this filter will do during the noisier hours of the day. The RMS at high frequencies doesn't look great, there will definitely be noise being injected into the YARM signal at high frequencies.

Measuring the YARM signal:

There is still noise being injected on YARM but it is definitely much better than the previous filter. I'm thinking about doing some IIR subtraction on the arms now to see if I can get rid of the noise that is being injected that way, but before I embark on that quest I will rething my prefiltering.

The plot below shows the ratio of the unfiltered versus filtered ASDs for the FIR and IIR subtraction predictions as well as for the measured online IIR subtraction. Positive dB means better subtraction.

Attachment 1: filter.png  213 kB  | Hide | Hide all
Attachment 2: stsx.png  143 kB  | Hide | Hide all
Attachment 3: mclonline.png  666 kB  | Hide | Hide all
Attachment 4: yarmonline.png  771 kB  | Hide | Hide all
Attachment 5: sub.png  145 kB  Uploaded Wed Aug 12 17:19:32 2015  | Hide | Hide all
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